1. Field of the Invention
The present invention relates generally to fluid actuated valve systems, and more particularly, to an air actuated valve system having an integrated seismic control circuit.
2. Description of the Related Art
Seismic valves which are used to shut off fluid flow upon experiencing a predetermined level of seismic activity are generally known. Where there is a high probability of seismic disturbances, such as earthquakes, seismic valves are necessary to prevent the release of hazardous and/or flammable substances such as natural gas and LPG.
One such seismic valve is described in U.S. Pat. No. 4,745,934 to Greer et al. The seismic valve is a pin supported gate valve having a gas-tight reset system. The seismic sensing component of the valve actuates shut off means when subjected to a predetermined amount and type of horizontal sinusoidal oscillation.
Although the seismic valve described above is effective for shutting off fluid flow, the valve is normally installed in a gas line between a meter and an associated structure. Due to the placement of the seismic valve directly in the fluid conduit, limitations are imposed upon the size of the conduit and the type of materials handled by the conduit.